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Author Topic: Solar attenuation  (Read 3098 times)

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Offline SoftWx

  • Posts: 832
    • SoftWx
Solar attenuation
« on: April 24, 2006, 11:30:05 AM »
Brian,

The solar attentuation used to produce the expected solar radiation (which is used to calculate %sunshine) overdoes it for my elevation and climate, especially around 2-3 hours after sunrise and before sunset. My solar values are actually greater than the expected solar value (107% of expected sunshine) when the %sunshine should be in the 80-90% range given the conditions.

I'm at 775 meters elevation, and in a desert climate with frequent conditions of very dry clear air.

Could you give the option of modifying the attenuation constant (0.5 I think). I'd like to be able to set it lower, as low as 0.

Thanks

Steve

Offline Weather Display

  • Posts: 74,411
  • Davis VP1
  • New Zealand
    • Weather Display
Re: Solar attenuation
« Reply #1 on: April 24, 2006, 06:46:45 PM »
HI
I have added this now, to the solar setup
download the new version from here
http://www.weather-display.com/downloadfiles/wdisplay32.exe
 :wink:

ps, after reading your comment on the CWOP windspeed, i will add option what time interval to use, 10 minute average (which  is an option at the moment) or 2 minute average.....(instead of 1 minute average)

Offline SoftWx

  • Posts: 832
    • SoftWx
Re: Solar attenuation
« Reply #2 on: April 25, 2006, 02:45:27 PM »
I'm watching the solar this morning and I've noticed that the percent sunshine and the Maximum radiation value still appear to be the values produced by the normal attenuation factor, even though I have set the Attenutation to 0 on the setup screen. The calculation doesn't seem to be using the value I enter on the setup screen.

Steve

Offline Weather Display

  • Posts: 74,411
  • Davis VP1
  • New Zealand
    • Weather Display
Re: Solar attenuation
« Reply #3 on: April 25, 2006, 07:00:24 PM »
have you clicked on OK on the solar setup screen?

Offline SoftWx

  • Posts: 832
    • SoftWx
Re: Solar attenuation
« Reply #4 on: April 25, 2006, 07:33:37 PM »
Yes, I clicked ok, and I also tried shutting down WD and restarting it. It shows 0 in the attenuation field, but the max solar and % possible sun appear to be calculated from the regular attenuation factor.

Steve

Offline Weather Display

  • Posts: 74,411
  • Davis VP1
  • New Zealand
    • Weather Display
Re: Solar attenuation
« Reply #5 on: April 25, 2006, 07:36:47 PM »
i see whats wrong....there was other places to change...

uploading a updated version, stand by...

Offline Weather Display

  • Posts: 74,411
  • Davis VP1
  • New Zealand
    • Weather Display
Re: Solar attenuation
« Reply #6 on: April 25, 2006, 07:47:06 PM »

Offline SoftWx

  • Posts: 832
    • SoftWx
Re: Solar attenuation
« Reply #7 on: April 25, 2006, 08:32:14 PM »
Yes, that's working better.

Thanks.

Steve